Battery Drain Mystery... need diagnostic guidance

[davidrrand]

Originally Posted by thiel

Hey Y'all,

I've been feeling for a while that my batteries just get depleted too quickly: if we camped out even a single night and used power sparingly (lights and fridge only!) we'd wind up below 11.9 the next morning.

When I last brought my trailer in for service, I had them check and load test both batteries, and things tested out fine. "Good and strong" they said.

In the past week, I've removed my inverter and installed a battery meter and shunt, and it's confirming that there's something very weird going on. Here are two data points:


6:26pm tonight
Trailer has been left plugged in with batteries charging for DAYS. With switch in "use" mode, the battery monitor (a Vicrton 712) should voltage at 13.68. Interior See Level monitor confirms the same. When I switch to "store" mode, the battery monitor drops down to 12.47 volts. I sync this voltage to 100% using the app.

7:23pm tonight
Still in "store" mode, I check the battery monitor. It shows 11.73v (but still 100% of charge). A multimeter across the battery terminals also shows 11.73v.

---

So... it appears that the battery monitor is working correct in terms of showing the voltage (but not clear why it still shows 100% state of charge.)

What could possibly be draining this so quickly?

I need so guidance on how to track down the problem here... sorta pulling my hair out.

Thanks in advance!

**************************************

I also have a 2016 AS. I have been reading posts on stock batteries for two years now. My Interstates were replaced after the first three months while traveling in Colorado. I am using the replacements and carefully maintain them, removing them from the trailer during winter and monthly correctly charge them. I am careful to not let the stock converter do its thing more than 72 hours and make sure the water level is good in each battery. I am having a PD4655VL installed this week which hopefully will improve converter charging. I also plan to upgrade to AGM batteries this fall if not sooner. I have come to the conclusion that two group 24 marine “deep cycle” are minimal at best for all the systems on a late model AS. Coupled with a single stage charger/converter, they are only sufficient for those who seldom boondock and rely on shore power most of the time. When new and fully charged they should get you through the night including running the furnace in 40F weather. Then they will probably require a charge again for at least 4-5 hours to get back to 90%. As they get older, this performance will worsen resulting in higher discharges requiring long charging times. There are so many things that drain these batteries and without regular solar or generator charging, they just don’t cut it. As previously mentioned these include the woofer & stereo, the invertor, the CO detector, the fridge fan, the electronics in the fridge and water heater, the TV antenna, and the furnace fan. Then add any appliances you might use while boondocking. Upgrading battery capacity and a means for keeping them charged properly is a requirement for better boondocking experiences, in my opinion.
Dave

[dmbecke]

Did you have the batteries tested?

[OTRA15]

Originally Posted by thiel

They are out of warranty, so I will probably cut to the chase and replace them if they test out bad in my driveway....

Next I'll be wondering what to replace them with. I don't think I will bother with AGMs, but a larger flooded battery that fits the box without modification would be great.

Wondering if the batteries were bad?

Thanks,

Peter

[thiel]

Tested one so far. Charged all night with an external charger. Charger indicated fully charged. Multimeter showed only 10.5 volts!

Testing the other one now.

[Al and Missy]

Originally Posted by thiel

Tested one so far. Charged all night with an external charger. Charger indicated fully charged. Multimeter showed only 10.5 volts!

Testing the other one now.

Dead cell in that one, possibly dragging the other one down. 2.1 x 5 = 10.5, 2.1 x 6 = 12.6.


Al

[OTRA15]

thiel my understanding is that only a battery store can test your batteries thoroughly, and give you an exact diagnosis. Prior suggestion applies to take them out ASAP and get them tested at an Interstate dealer, who can replace them both on the spot if one is bad.

[thiel]

Originally Posted by OTRA15

thiel my understanding is that only a battery store can test your batteries thoroughly, and give you an exact diagnosis. Prior suggestion applies to take them out ASAP and get them tested at an Interstate dealer, who can replace them both on the spot if one is bad.

Yeah... I was really just wondering whether there was something obvious wrong, and apparently there is!

Also, since I paid an RV dealer to test them... but one won't charge past 10.5 volts, then I think I need to have a conversation with that RV dealer.

I found an Interstate dealer nearby. They seemed to know what they were doing, so we'll see what happens next!

[Bill M.]

Do AGM's give more usable capacity than flooded cell batteries of the same group size?

[wulfraat]

Originally Posted by Bill M.

Do AGM's give more usable capacity than flooded cell batteries of the same group size?

Generally speaking, yes.

[thiel]

Picked up two Group 27 batteries today.

I was able to get them into the battery box without removing anything... but I did have to give the second battery a gentle kick to do it. If I removed the hinge--without modifying the box--then they would have slid in without any hangups at all.

All seems to be working well now. Charge monitor now makes sense, I can see how much power everything is using... and the 27s give me some more capacity at a low price.

Thanks for all the help gang!

[OTRA15]

Thanks for the update. Did you get any confirmation from the battery store that the old batteries had some bad cells, or any other reason for their bad performance? It would be good to know what went wrong IMO. Otherwise this adventure will not be the learning experience it could have been.

Any discount due to the old batteries not performing fully, within the Interstate battery warranty period [separate from AS warranty]?

Thanks,

Peter

[OTRA15]

Originally Posted by thiel

Picked up two Group 27 batteries today.
. . .

Wondering if the battery store gave you any feedback on why the old batteries failed?


Thanks,


Peter